Increasing sophistication and complexity of electric equipment installed in cars and other vehicles led to increasing diversification of the connectors used for connecting such equipment. Generally, an increase in the number of contacts in a connector results in a stronger force required for joining matching halves of the connector, to a degree that, in some cases, manual connection becomes extremely difficult or even impossible. Therefore, a number of designs were suggested in which one connector housing has a nut and the other connector housing has a bolt, and their joining is carried out using nut and bolt threads by means, for example, an air screw or bolt driver. FIG. 6 is a cross section of an embodiment of a conventional connector with bolt fastening means disclosed in Japanese UM Publication (1990)-59584. In this embodiment, nut 102 is embedded in one connector housing 100, and bolt 120 is retained in the other connector housing 110 by means of a push nut 130.
The push nut 130 retains the bolt 120 due to friction between its blades 132 and cylindrical surface 122 of the bolt along its axis. In order to prevent disengagement of the bolt 120 from the push nut 130 and to provide resistance against a force pulling apart the pair of connectors 100, 110, it is necessary to create a strong friction between the blades 132 and the cylindrical surface 122 of the bolt 120. Because of this, a special tool is used for fitting the push nut 130 over the cylindrical surface of the bolt 120, thus making the operation of securing the bolt 120 in the housing 110 rather complicated. Another disadvantage of this design consists in a non-uniform quality of connectors due to the fact that the blades 132 move along a straight surface of the bolt 120 without a specified location to stop. The fact that the head 124 of the bolt 120 extends above the surface of the connector housing 110 may be a problem in using robots for automatic insertion of contacts (not shown in the drawing).
In order to overcome this problem, a bolt-fastened connector shown in FIG. 7 and disclosed in Japanese Patent Publication (1987)-188188 was offered in which the bolt retaining housing 210 is separate from the main housing 200 and is inserted in the compartment 202 of the main housing 200 after contact insertion operation is completed. In this bolt-fastened connector, the bolt 220 is retained in the bolt-retaining housing 210 by means of a stopper (not shown in the drawing), and the bolt-retaining housing 210 is held in the main housing 200 by means of latches 212 made integral with the housing which are engaged in the latching recesses 204 in the main housing 200.
However, in such bolt-fastened connectors made of two housings 200 and 210, the operation of fixing the bolt 220 in the bolt-retaining housing 210 requires special tooling, and the operation itself is not easy. Moreover, since the disconnecting of this connector from a matable connector (not shown in the drawing) requires rather large effort, the latches 212 and the recesses 204 must be rather large to withstand such forces applied to them during disconnecting. Because of this, the devices provided specifically for securing the bolt-retaining housing 210 in the main housing 200 occupy a considerably large area, thus compromising compactness of the connector. In an event of damage caused by the overtightening of the bolt 220, it is necessary to replace the entire bolt-retaining housing 210. However, since the latches 212 are locked in the compartment 202, removal of the bolt-retaining housing presents certain difficulties.
For this reason, a bolt-fastened connector (shown in FIG. 11) was proposed in which the bolt 330 and the bolt retaining housing 320 are fixed to the main housing 300 by means of a flat plate 310 fitting over the neck 332 of the bolt 330 as disclosed in Japanese UM Publication (1992)-32702. The operation related to the installation of the bolt 330 in this bolt-fastened connector is relatively easy, because no push nuts, stoppers or similar parts are required. In addition, because the bolt retaining housing 320 is joined to the main housing 300 indirectly by means of the bolt 330 and the plate 310, it can be easily removed from the main housing 300 by breaking the neck 332 of the bolt 330.
However, application of such a design with a plate for the fixing of the bolt to a connector with multiple contacts shown in FIG. 7, may result in the following problem. Since the opening for the retaining plate intersects the contact receptacle chamber, the plate reduces the useful area available for contacts, thus compromising compactness of the connector and density of contacts in it.